Lesson: Coherent Light Physics • 9th Grade

In this lesson, we will learn how to determine whether two or more electromagnetic waves will interfere to form coherent or incoherent light.

Lesson Plan

Students will be able to

recognize that two or more waves are coherent if they have the same frequency and a constant phase difference from each other,
recognize that two or more waves are incoherent if they have different frequencies or a nonconstant phase difference from each other,
determine, by looking at the waveforms, whether a set of waves are coherent or incoherent,
determine, by looking at functions that describe basic waveforms, whether a set of waves are coherent or incoherent.

Q1:

Which of the following statements correctly defines what is meant by the term “coherent light”?

Q2:

Which of the following statements correctly defines what is meant by incoherent light?

Q3:

The figure shows five light waves. Which light wave is not coherent with the other four?